Apparatus for heating material



May 4, 1943- J. N. sELvlG 2,318,533

` APPARATUS FOR HEATING MATERIAL Filed Dec. 6, 1940 'lllllll/I.

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NI/ENTOR J. N. SLVG A T TORNEY May 4, 1943 i UNITED; STATES PATENT ko1-*Fics t 2.31am Y .A

. arrasa'rus Foa mismo Marsman .una N; servis, wensen, N. J., mim: u wen- Eiactric Company, Incorporated, New York, N. Y., a corporation oi New York al wire coated with one or another form of elec-l trically insulating or otherwise protecting material has long been practised by methods and apparatus involving exposures to radiant heat from oven surfaces, electrically heated resistance elements, and the like. There are three fundamental ends to beaimedk at in all such methods and apparatus, namely, to apply heat to the strand equally from all sides at each point of the exposed portion, to apply the heat along the strand without excessive temperatures at any part of the portion exposed to the heat, and to minimize tensional stresses in the heated portion. This last point is one whose importance is not always appreciated. especially in the case of electrical conductor wires oi' copper or of aluminum or of other metals or metallic alloys of highv conductivity but sometimes also of high malleability and relatively low tensile strength especially when heated. In a particular case, wires of high conductivity copper have recently been provided with an insulating sheath of ielted cellulosic or textile nbres formed directly on the wire as a seamless envelope of wet pulp and then dried. Inv f ther instance, auch wires are cov? ered with threads served. braided or knitted int'falseamiess envelope and subsequently coated with'a solid material, e. g. cellulose acetate, in a liquid solvent or vehicle, e. g. acetone, and are then heated to dry out the solvent or vehicle. In such cases the sheathed wires have been passed through long vertical chambers or through long horizontal .chambers while being subiected to radiant heat from oven walls, electrical resistance elements or the like. When passed through vertical drying chambers, there is no diiiiculty in applying the heat uniformly to all sides of the wet sheathed wire, since the wire may hang free in its passage'from one guide sheave to another; but the weight of the iree hanging length of the wire is superimposed on the tension in the wire caused by whatever means is employed to pull the wire through the apparatus, and this weight may be great enough to cause stretching of the heated wire with consequent damage both to the wire and to the sheath thereon. A similar difficulty arises in the case eatenary practicably shallow may well exceed the tension due to the weight of the wire in a vertical chamber. Attempts have been made to utilize a horizontal chamber in which such superadded tensions are avoided by supporting the wire dur- 5 ing its passage through the heated acne. This,

of course, avoids theweight tensions; but obviously introduces problems of applying heat equally to all sides of the wire because of obstruction by the supporting means employed.

An object of the present invention is to provide apparatus for heating strand material uni formly without any necessity for weight tension on the strand while being heated.

With the above and other .objects in view, the invention may be embodied in an apparatus wherein strands to be heated are advanced horizontally over while being supported on a flat horizontal secondarily radiant surface, and while primary radiant heat is supplied from above to substantially evenly envelope each strand in combined primary and secondary radiant heat.

Other objects and features of the invention will appear from the following detailed description of one embodiment of the invention in an apparatus constructed in accordance with the invention, taken in connection with the accompanying drawing in which the same referencenumerals are applied toY identical parts in the several ngures and in which Fig. l is a generalby diagrammatic view of a part of the apparatus in side elevation and partly in section;

Fig. 2 is an enlarged view thereof in end elevation and partly in section;

Fig. 3 is a partial view of the showing of Fig. 2 in longitudinal vertical section;

Fig. 4 is an enlarged fragmentary section on the line '4-4 of Fig. 3;

Fig. 5 is a further enlarged view similar to Fig. 4 of `o. modified form;

Fig. dis a corresponding view of another modified form; and

Fig. 7 is a corresponding view of still another modified form.

As herein disclosed, strands 2l comprise a core 2| and a covering, coating or sheath 22 and are to be uniformly heated while passing through the apparatus shown, being advanced by means not shown.

'I'he apparatus comprises a bed or base Il havlng the general form of a long blockvor slab of some suitable material,` preferably a relatively .good heat insulating substance such as cement,

concrete, ceramic blocks or bricks, or the like. la Preferably inset into the fiat horizontal top surface of the base is a wide. shallow troughrll of sheet metal having a generally nat bottom and vertically upturned side flanges.G Vertical .side wall members 32 of sheet metal are backed along their lower edges against these upturned danses and are supported by suitable posts 33 positioned at intervals against their outside faces and on the bed 30.

Suitable sources of primary radiant heat auch as infrared lamps 4l arefsupported over the channel formed by the trough 3| and walls 32 to direct substantially parallel bundles of rays of primary radiant heat down into the channel. These lamps are preferably arranged in pairs transversely opposite each other so that one lamp of each pair directs its rays 4| slantingly down against the right hand wall 32 (Fig. 2) and not less than half the width of the floor of the channel, while the other lamp of the pair similarly directs its rays 42 slantingly down against the left hand wall 32 and not less than half the width of the floor.A Radiation thus directed against the floor of the channel either directlyV from the lamps or by reection from the walls 22 will be termed primary radiation; while radiaticn coming up from the floor member whether by reflection or otherwiserwill be termed secondary radiation.

The inner faces of the walls 32 are highly polished and are preferably coated with polished gold to provide as durable and as perfectly refleeting a surface as possible.

The upper surface of the floor member 3| may be treated in either of two ways, by which the same end result is achieved but in somewhat differing fashions. This surface may also be a reflector, e. g. gold plated and polished, which will reflect a maximum and absorb a minimum of radiant energy falling upon it. Or it may be a black body surface treated to reflect a minimum and absorb a maximum of radiant energy. If the member 3| be made of iron or steel and its top surface phosphatiaed to produce the familiar minutely rough, matt, substantially black surface characteristic of surfaces rust proofed by phosphatizing, a substantially black body surface is created, suitable for the present use.

In the preferred embodiment, shown in Figs. 1 through 4, the floor is'treated to have a black body surface and is also provided with a number of spaced, transverse, narrow upstanding ridges whose height is about the same as the thickness of the strands 2l to be treated. These ridges 34 are of practically negligible width along the strands, and are spaced at such distances apart as to support the strands at points close enough together to obviate any material sagging of the strands between ridges as the strands are drawn along over them.

The lamps 40 are so placed as to the directions of their rays that the .condition disclosed ln Fig. 4 is substantially achieved, namely, that no part ofthe floor 3| is wholly shaded by a strand 20 from both lamps. The shadow in the bundle of rays 4|- is wholly irradiated by the bundle 42; and the shadow in 42 is wholly irradiated by 4|. Thus the upper surface of the strand 2li down to the points 23 and 24 is irradiated by primary radiation .either directly from the lamps or reflected from the side walls.

The top surface of the bottom member 3| being a black body surface, absorbs the radiant energy falling upon it practically entirely and reflects practically none. This absorbed radiant energy is converted in the body of the member 3| into kinetic heat energy and raises the temperature of its substance to a point where there is equilibrium between energy falling upon it and energy re-radiated from the black body surface. Thisre-radiated energy is radiated vertically up from the horizontal top surface ofthe member 3| as indicatedrat 43 in Fig. 4 and thus irradiates the under` surface of the wire 2B.' 'I'hus the wire is subjected to `substantially.uniform radiant energy on aIlsides due to the combined primary and secondary radiationV thus provided.

A number of strands may be simultaneously treated in this manner, as indicated in Fig. 2, by running them over the member 3| parallel to each other, and spaced from each other a distanceV apart preferably not less than their own diameters.

In the modification shown in Fig. 5,*the memy ber 3| has the same transverse ridgesV 34 as before, but its top surface is made as nearly totally reflecting as possible. from below in such case, is reflected and comes up from the reflecting surface slanting'the same amount from the perpendicular as the primary radiation, instead of vertically as in Fig. 4. Each wire 20', however, is again irradiated substantially equally on all sides.

As modified in Fig. 6, the ridges 34 are omitted and the top surface of the member 3| is treated to be a black body surface. In this case the strands are supported at every point of their length along the member 3|. Since each strand 2|| thus lies directly tangent to the surface of the member 3|, Va portion of the surface directly under the strand will be shadowed by the strand from the primary radiation. However, there are portions of this surface between the strands and wider than the distance between the strands which will be irradiated with primary radiation and will absorb energy. Since the member 3| is of metal this energy will be distributed substantially evenly throughout its substance and will be re-radiated as secondary radiation directly up under each strand from the portion of surface under the same. Thus a satisfactory result is achieved in this case also.

Fig. 7 shows the case where the ridges 34 are omittedy and the top surface of the member 3| is made reflecting. Here there should in theory be an unsatisfactory irradiation of a small portion of the surface of the strand on each side of its line of tangency with the surface of the member 3|. However, in practise no metallic surface is truly totally reflecting, and there will be sufflcient black body radiation directly under the strand to supplement the reflected radiation satisfactorily. The same mixed effect will, of course, also characterize the arrangement of Fig. 5.

Only so much of the apparatus is herein disclosed as is needed to describe and delimit the invention. In practice there may be required means to remove and carry away water vapors, solvent fumes and the like liberated from the strand by the heat applied in the manner described. Also means are required to propel the strands, preferably at a uniform rate, longitudinally through the apparatus. vSuch means are no part of the invention and so are not shown. The specific structure and mode of operation of the heat radiating means 40 are also no part of the invention, it being merely required for the purposes'of the inventionthat these means or lamps project radiant heat in bundles of substantially parallel rays. Details of a suitable radiant heat projector for the lpresent purposesr The secondary radiation' may be found, if desired, however, in U. S. Patent 2,057,776 of October 20, 1936 to F. J. Groven.

'I'he embodiments of the invention herein disclosed are illustrative and may be variously modifled and departed from without departing from the spirit and scope oi the invention as pointed out in the appended claim.

What is claimed is:

An apparatus for heating material in strand form and comprising members to form an open topped channel with vertical side walls and with a horizontal door to support a strand passing over the oor and between the walls, the inner faces of the side walls being polished to reiiect radiant heat and the tloor surface being blackened to radiate secondary radiant heat by black body radiation when irradiated with primary radiant heat, in combination with a plurality of sources of primary radiant heat positioned to irradiate the inner faces of the side walls and the floor surface with primary radiant heat from two angularly diverging directions simultaneously and thereby to irradiate a strand passing'through the channel upon its upper portion with primary radiant heat and upon its lower portion with secondary radiant heat radi-V ated by black body radiation from the iioor lurface.

JOHN N. SELVIG. 

